Method of making balls



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METHOD OF MAKING BALLS 2 Sheets-Sheet 1 Filed Sept. 5, 1963 I JTI.

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METHOD OF MAKING BALLS Filed Sept. 5, 1963 2 Sheets-Sheet 2 n van forTAKEFUSA K/KUCH/ United States Patent 3,206,828 METHOD OF MAKING BALLSTakefusa Kikuchi, Tokyo, Japan, assignor to Taiyu Shojr KabushikiKaisha, Chiyoda-ku, Tokyo-t0, Japan Filed Sept. 5, 1963, Ser. No.306,907 Claims priority, application Japan, Feb. 16, 1963, 38/ 8,018 1Claim. '(Cl. 29-1484) This invention relates to a manufacturing methodof steel balls with a uniform surface fiber structure out of a roundbar, by hot rolling.

One of the most important characteristics of steel balls, which are usedeither for ball bearings or for grinding purposes, is to have uniformmechanical properties not only throughout the ball, but also, all overthe surface of the ball.

Such condition is obtained when the structure of material is eithercompletely uniform throughout the ball, or concentrically uniform aroundthe center of the ball like golf balls or baseballs. Steel balls withsuch structure as above mentioned are the ideal balls.

In the case of balls which have been forged or rolled out of steel barsby conventional methods, such as by drop hammers, upsetters or rollingmills, parallel structural fibers of the bar are cut transversely, andthe sections of these fibers come out in the surface of the ball, andthe parallel fibers of the original bar remain almost unchanged withinthe ball, as shown in FIG. 7. This illustrates that the mechanicalproperties are neither uniform throughout the ball, nor concentricallyuniform around the center of the ball. Such balls, when used for ballbearings, will afford uneven rolling resistances, and when used forgrinding purposes, will wear unevenly.

This invention eliminates the defectives as above mentioned, byconcentrating all the sections of structural fibers to one point on theball surface, and by covering the ball surface with uniform rolled layerof structural fibers, so that the sections of structural fibers are notexposed on the surface of the ball, and moreover, within the ball thefibers are bent and curved around the ball center, as shown in FIG. 6.

Thus, this invention is a method to roll ideal or nearly ideal ballseconomically out of a round bar.

In the accompanying drawings, :FIG. 1, FIG. 2, FIG. 3, FIG. 4 and FIG. 5are the sectional views, showing the progress how a ball is rolled outof a bar, FIG. 6 is the sectional view along the structural fiberswithin the ball rolled by the invented method, FIG. 7 is the sectionalview of a ball, manufactured by the conventional methods, showing thefiber structures within the ball. FIG. 8a, FIG. 8b and FIG. 8c are thesectional side views along Y-Y respectively in FIG. 9a, FIG. 9b and FIG.90. FIG. 9a, FIG. 9b and FIG. 90 are the sectional views along Z-Z inFIG. 8a, FIG. 8b and FIG. 8c, and FIG. 10 is the sectional perspectiveview along X--X in FIG. 8b, and show one of the embodiments of theinvented method to roll a ball.

As shown in FIG. 8a, FIG. 8b, FIG. 80, FIG. 9a, FIG. 9b, FIG. 90 andFIG. 10 a round bar 5 is inserted transversely between a pair of rollingdies 1. Each of the dies 1 has a set of equally shaped ridges 2 and agroove 3 as shown in FIG. 9b.

The ridge 2 has a uniformly increasing height h as shown in FIG. 8s andFIG. 9s, and a uniformly decreasing top breadth 1 as shown in FIG. 10,and thus forming between them the groove 3 with a uniformly increasingwidth w and depth h as shown in FIG. 10 and FIG. 8s. The profile of thecross section of the groove 3 is a circular arc, whose radius is equalto the radius of the ball to be rolled, and the cross section of the topof "ice the ridge 2 is a straight line as represented by 2 which isparallel to the center line of the round bar 5, as shown in FIG. 9s.

The ridges 2 as well as the groove 3 start at B, and end at E, as shownin FIG. 8s, where .the profile of the cross section of the groovebecomes a complete semi-circle as shown in FIG. 90.

The rolling dies 1 are, as shown in FIG. 8s, arranged face to face butto be shifted longitudinally to the opposite directions as shown byarrows A in FIG. 8s, so that the bottom lines BE of the grooves 3 arekept parallel with each other at a distance equal to the diameter of aball to be rolled.

In order to roll a ball, a bar 5 is inserted transversely between the'dies 1, then the dies are shifted longitudinally towards the oppositedirections as above described. The dies will then catchthe bar by ridges2 at the points B where the ridges start as shown in FIG. 8a, and thenthe ridges and the groove will gradually roll the bar, as shown in FIG.8b, till at last the dies finish their rolling process at E, where theprofiles of the cross section of the groove is a complete semi-circle toproduce a spherical ball 6, as shown in FIG. 86.

In the course of rolling, the top surfaces S of the ridges 2, whosecross section are straight lines 2", press the bar radially withpressure p, and the breadth 1 of the surface S gradually decreases to ll l l and so on, as FIG. 1, FIG. 2, FIG. 3 and FIG. 4, till at lastbecomes zero where the rolling is completed as shown in FIG. 5, FIG. andFIG. 90.

Certain molecules, as represented by a, b, c, d, e, f, g, h and i inFIG. 1, on the surface of the round bar 5, will be removed successivelyand respectively to a, b, c, d, e, f, g, h and i as shown in FIG. 2,FIG. 3, FIG. 4 and FIG. 5, as rolling proceeds, where the distance L,between the points a and i, as shown in FIG. 1, increases gradually andsuccessively to L L L and L as rolling proceeds, as shown in FIG. 2,FIG. 3, FIG. 4 and FIG. 5.

Moreover, while the bar 5 is rolled from the state as shown in FIG. 1 tothe state as shown in FIG. 2, the molecules b, c, d, e, f, g and h areradially removed respectively to b, c, d, e, f and g as shown in FIG. 2,and the portion of structural fiber F between the molecules at and b, aswell as the fiber between the molecules h and i are both elongated tofinish a portion ab as well as a portion hi of a complete sphericalball.

These portions ab and hi of the ball have been rolled and finished bythe rolling groove 3. In the same way, other molecules as c, d, e, f,and g are radially removed successively from their positions as shown inFIG. 3 to their respective positions on the surface of the ball as shownin FIG. 4 and so on, till at last the last molecule e reaches to theaxis of the bar, when the rolling process is finished to produce acomplete spherical ball 6, as shown in FIG. 5, FIG. 80 and FIG. 90.

Thus, it is clear that the portion ab as well as hi, which has beenrolled and finished to compose a portion of spherical surface of theball as shown in FIG. 2, will not further be rolled again. In the sameWay, the portion be and portion gh, which have been finished in the nextprocess, will not further be rolled, and so on, till at last themolecule e reaches the axis of the bar. This process that the ball isrolled by the rolling groove is one of the typical features of thisinvention.

The ball being rolled like this, it is clear that the whole surface ofthe ball is covered by fibers F which originally covered the cylindricalsurface of the bar 5 and which have been elongated as above described.Similarly all other internal fibers F, having been indirectly rolled bythe dies through respective outer layer of fibers, are also bent curvedrespectively and reversely proportional to an amount to their respectivedistance from the axis of the bar.

Thus the ball, which has been rolled by the invented method as abovedescribed, becomes composed of layers of structural fibers, theoutermost of which is a complete spherical layer, which covers thesurface of the ball, and the inner fibers F compose successive layers,each of which being nearly concentric and oval, just like layers inonions, as shown in FIG. 6.

The reason why the fiber structure becomes as above described, is to befurther explained as follows:

As already described, during the rolling process, the portion of thebar, such as bh in FIG. 2 or d in FIG. 4 is pressed radially withpressure 1 towards the axis of the bar by the surface S of the ridge ofuniformly decreasing breadth l, which is a straight line parallel to theaxis of the bar 5. Therefore, practically no axial force acts on thesaid portion of the bar, to pull apart the bar along this portion, andtherefore, the rolled ball separates of itself when the rolling processis completed, without being pulled off the bar before the process iscompleted. Therefore, all fibers concentrate to one point Q on thesurface of the ball, as shown in FIG. 6. This is another special featureof the process of this invention.

Thus, the fiber structure of the ball, rolled out of a round bar, by theinvented method is very near to an ideal spherical ball.

The roll method as above described, is one of the embodiments of thisinvention, in which, the rolling ridges and groove are straight andequipped on the surfaces of a pair of plane rolling dies. But actually,these ridges and groove may be equipped, either spirally on the surfacesof a pair of plane circular discs, or helically on the surface of a pairof cylindrical rolling mills.

I claim:

A ball manufacturing method by rolling with a pair of opposed rollingdies, each of which has a set of rolling grooves whose cross sectionbeing a circular arc of like radius, said grooves extendinglongitudinally of said die throughout the length thereof andprogressively increasing in depth from one end to the terminal end, thedepth of each of the grooves at the terminal end being equal to saidradius, said grooves forming ribs therebetween, each of said ribsdecreasing in width from one end to said terminal end where it forms asharp pointed edge, the grooves in said opposed dies being reverselyarranged, inserting between said dies a cylindrical bar to be rolledinto balls, shifting said dies toward opposite directions with rollingpressure acting radially on the bar, deforming said bar gradually towardthe coacting terminal ends of said dies and ribs thereof to graduallyform the balls and separate them in finished form by the opposed sharppointed edges at the ends of said ribs.

References Cited by the Examiner UNITED STATES PATENTS 2,700,908 2/55Bockting 7293 WHITMORE A. WILTZ, Primary Examiner.

THOMAS H. EAGER, Examiner.

